The present invention relates to a method for manufacturing a product in a form of a mat containing mineral fibers and a binding agent, in which method the binding agent is mixed together with the fibers before the formation of the product.
In the manufacture of mats formed of mineral fibers, the fibers are produced by conveying melted material on centrifugal wheels or inside perforated drums which sling the material by the centrifugal force outwards as thin fibrous pieces. At the same time, air is blown from the side of the centrifugal wheels in a direction perpendicular to the slinging direction, whereby the pieces are simultaneously directed to a certain direction and cooled down by air. The fibers are carried by the air flow onto an air-permeable support, through which the air flow passes, and on this support they form a felt, which is conveyed by the support to aftertreatment devices. Production methods of this kind are described, for example, in Finnish Patents No. 76842 and 77272.
For binding mineral fibers into a homogeneous mat, a suitable liquid binding agent, which will harden, is sprayed on the fibers in fluid form before the settling of the fibers into a mat. At the same time as the fibers are formed, a suitable cooling agent, such as water, is mixed with them for securing a sufficiently quick cooling of the fibers. Next, the matting formed on the support is usually subjected to heat treatment by raising its temperature again for hardening the binding agent, at which stage the final density and thickness of the product is determined. After this, the product can be worked further in a number of ways, for example, by sawing, cutting, or the like.
In the present application, the term mineral fibers is used to denote stone fibers, glass fibers, ceramic fibers, or slag fibers.
In the prior art methods mentioned above, the binding agent in general use is phenol-based resin which is sprayed on the surface of the fibers and used for hardening the mat at the later stage of heat treatment. A problem with the use of such resin lies in the environmental and health risks involved. Furthermore, a long heating time and, respectively, a long heating oven is required for hardening the resin, thus increasing the costs on investment and energy in the lines of mat manufacture.